Traditional Posters: Miscellaneous

Changho Choi¹, Aditya Patel<sup>1

1</sup>Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States

Serine (Ser) in human brain, which has coupled proton resonances at 3.98, 3.94, and 3.83 ppm, is difficult to measure because of its relatively low concentration (~0.5 mM) and the spectral overlap with the creatine (Cr) 3.92 ppm resonance. Constant-TE difference editing strategies for detection of Ser at 3T have been explored. Echo time dependence of the Ser multiplet was investigated, with density-matrix simulation, for point-resolved spectroscopy and triple refocusing. The Ser multiplets in sub- and difference-spectra were in good agreement between simulation and phantom experiments. In vivo feasibility of the difference editing methods is discussed with results from a phantom with physiological concentrations of Ser and Cr.

935. Short VAPOR-Like Water Suppression with Improved Water Suppression Performance Suitable for High Field MRS and MRSI Exploiting the Residual Water Signal as a Reference

Zenon Starcuk jr. ¹, Zenon Starcuk¹, Jana Starcukova<sup>1

1</sup>Magnetic Resonance & Bioinformatics, Institute of Scientific Instruments, Acad. Sci. Czech Rep., Brno, Czech Republic

A short VAPOR-like water suppression sequence is presented, exhibiting similarly low B1 and T1 sensitivity and improved excitation profiles. The improvements are based on optimization of flip angles and pulse durations of chemical-shift selective pulses interleaved with fixed short delays. The sequence consists of 6-pulse water presaturation with asymmetric RF pulses, followed by B1-insensitive inversion and the localization module. The improved robustness may be utilized for an accurate control of residual water signal and exploiting it as a reference. Thanks to the reduced length and reduced impact on metabolites, the sequence should improve quantifiability and be suitable for spectroscopic imaging.

936. Anomalous Lipid Signal Investigation When Measuring Water/Lipid Signal with Unsuppressed 1H MR Spectroscopy

Victor Rakesh Lazar¹, David J. Manton², Timo Schirmer³, Ralph Noeske³, Gary P. Liney⁴, Martin Lowry⁵, Mark Lorch⁶, Lindsay W. Turnbull<sup>5

1</sup>Centre for MR Investigations, University of Hull, Hull, North Humberside, United Kingdom; ²CMRI, University of Hull, Hull, United Kingdom; ³GE Healthcare; ⁴Radiotherapy Physics, Queen's Centre for Oncology, Hull, North Humberside, United Kingdom; ⁵CMRI, University of Hull, Hull, North Humberside, United Kingdom; ⁶Department of Chemistry, University of Hull, Hull, North Humberside, United Kingdom

Water:lipid signal ratio (WLSR) can be measured with unsuppressed 1H MR spectroscopy and such data can be used to characterise breast cancer and bone disease. It is important, however, to be aware of potential bias (systematic errors) in these measurements as caused by chemical shift-induced voxel offsets which will be relatively large for the 3.4 p.p.m. water-lipid separation. Preliminary investigation and results related to this condition has been explained.

937. Using 3T Magnetic Resonance Spectroscopy to Assess the Long Term Effects of Mild Traumatic Brain Injury

Lisa Maria Harris¹, Phil Dean¹, Annette Sterr<sup>1

1</sup>Psychology, University of Surrey, Guildford, Surrey, United Kingdom

Mild traumatic brain injury (mTBI) typically induces a set of symptoms, including poor memory, collectively referred to as Post Concussion Syndrome (PCS). A combination of a working memory task and magnetic resonance spectroscopy was used in a study to investigate the link between metabolite alterations, PCS symptoms and working memory ability in mTBI participants at least one year post injury. Lactate showed a significant positive correlation with PCS symptoms, this is usually elevated in the acute phase. There was also a trend towards high lipids and macromolecules in those with more PCS symptoms.

938. Determination of Brain Histidine Concentrations and Kinetic Modeling of Human Blood Brain Barrier Transport

Daniel Guo Quae Chong¹, Jean-Marc Nuoffer², Christine Sandra Bolliger¹, Peter Vermathen¹, Chris Boesch¹, Roland Kreis<sup>1

1</sup>Department of Clinical Research, University Bern, Bern, Switzerland; ²Departement Hämatologie, Onkologie, Infektiologie, Labor-Medizin und Spitalpharmazie (DOLS), Inselspital, Bern, Switzerland

Normal human blood and brain histidine concentrations were measured over a 10 hour period after an oral load. On average, blood histidine concentrations reached a maximum of 3.5 mM while brain histidine peaked at 1.9 mM, 5 hours after blood. Applying the symmetric Michaelis-Menten kinetics resulted in kinetic parameters of maximum transport of 23 nmol/g/min, an apparent Michaelis constant of 2.1 mM and a cerebral metabolization rate of 0.3 nmol/g/min. The complexity of the system investigated and various factors render the data inconclusive upon the appropriate kinetic model and potential subject dependence of the kinetics.

939. Single Voxel 1H Spectroscopy in the Human Hippocampus at 3 T Using LASER: A Reproducibility Study.

Najib Allaïli^1,2, Malgorzata Marjanska³, Edward J. Auerbach³, Eric Bardinet¹, Philippe Fossati⁴, Romain Valabrègue¹, Stéphane Lehéricy<sup>1

1</sup>CRICM (CENIR), UPMC/INSERM UMRS 975/ CNRS UMR 7225, Hôpital Pitié-Salpêtrière, Paris, France; ²Centre Emotion CNRS USR 3246, Paris, France; ³Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN, United States; ⁴Centre Emotion CNRS USR 3246, Hôpital Pitié-Salpêtrière, 47 bd de l'Hôpital 75013 Paris, France

Scan to scan reproducibility is challenging, especially in the deep brain regions such as hippocampus where lower SNR and poor magnetic field homogeneity can lead to larger uncertainties in metabolite quantification. Few studies have investigated 1H-MRS reproducibility in the hippocampus either at low magnetic field strength or with few subjects. Relatively large VOI were used in most of these studies, resulting in partial volume effects. In this study, we investigated the reproducibility of spectroscopic measurements in the hippocampus at 3 tesla using a LASER sequence . We performed our measurements in a 2.4 mL volume to minimize partial volume effects.

940. Simultaneously Assessed GABA/Glutamate/Glutamine Concentration Gender Differences at 3.0T